Mechanical properties of maize stalk as related to harvesting

Abstract

Experiments were carried out to determine the optimum values of bevel angle, knife approach angle, shear angle and knife velocity for cutting maize stalks. The effects of cross-sectional area and moisture content of the maize stalk on cutting energy and cutting force was studied. The effect of rate of deformation on mechanical properties such as ultimate shear strength, shear energy, ultimate compressive strength perpendicular to plant axis and modulus of toughness was also studied. A pendulum type impact shear test apparatus was used to determine the cutting energy requirement of the stalk. Maize stalks of Ganga Safed-2 hybrid variety were used as the experimental material. The ultimate shear strength, shear energy, ultimate compressive strength in transverse direction and modulus of toughness of stalk were determined by a table model Instron testing machine. Knife bevel angle of 23°, knife approach angle of 32°, shear angle of about 55° and the knife velocity of about 2·65 m/s were shown to be optimum. The cutting energy and maximum cutting force were directly proportional to the cross-sectional area and inversely proportional to the moisture content of the stalk. The ultimate shear strength, shear energy, ultimate compressive strength in the transverse direction and modulus of toughness were observed to decrease with increase in rate of deformation.